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Po-Kang Lin, Chien-Chao Chiu, Chia-Ying Ke, Yih-Jing Lee; Effects of anti-VEGFs on choroidal vessel outgrowth by an hcy-evoked choroidal capillary sprouting explant model. Invest. Ophthalmol. Vis. Sci. 2016;57(12):4521.
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© ARVO (1962-2015); The Authors (2016-present)
We have previously reported that plasma homocysteine (hcy) levels were notably high in PCV patients. To investigate hcy-related choroidal angiogenesis, we established an ex vivo choroidal capillary sprouting explant model, and examined the blocking effects of commonly used anti-VEGFs on choroidal vessel outgrowth in this model.
Chorioretinal explants from C57BL/6 mice were used. The choroid/sclera (containing the retina, RPE layer and choroid) fragments were isolated and mounted soon after the animals were euthanized. Medium with different concentration of hcy was added to each explant well. Anti-VEGFs were added as objects. The choroidal explants were observed at different time point, and the total area of capillary sprouting was measured and analyzed. The expressions of vascular cell markers Isolectin IB4, vascular endothelial growth factor (VEGF), and placental growth factor (PlGF) were also studied using immunofluorescence staining. Aflibercept and ranibizumab were subsequently added for blocking the sprouting.
The choroidal vessel outgrowth effect of hcy can only be observed within a certain range of concentrations. The explants treated with 1 mM hcy showed significantly increased capillary sprouting areas. Probable growth factors for neovascularization were detected by immunofluorescent staining, and the results showed PlGF was upregulated only in the hcy-treated preparations. Adding aflibercept to the hcy-treated chorioretinal explants halted the increase of the capillary sprouting area. However, ranibizumab did not. The difference suggested that aflibercept might inhibit the angiogenesis in the choroid caused by hcy owing to its unique feature of trapping both VEGF and PlGF.
We found aflibercept capable of reducing hcy-induced choroidal capillary sprouting, instead of ranibizumab. Immunohistochemical study also showed PlGF was upregulated in hcy-treated explants. Since aflibercept could inhibit PlGF, but ranibizumab, we conclude that PlGF might play a key role in the choroid angiogenesis caused by hcy.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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